The rise of Bristol to a position of commercial prominence was very much bound up with the transatlantic economy, so that any long-term transformations to that economy inevitably affected its status. The war with America and the eventual declaration of independence wrought significant changes in Bristol's relationship with the North American colonies; by extension it also altered the dynamic of its trade with the West Indies. In the decade after the Seven Years’ War Bristol's American trade grew spectacularly. From September 1763 until September 1764, eighty-one ships entered Bristol from British North America, carrying 6798 tons of merchandise; the corresponding figures for 1774–75 were 175 ships and 20,561 tons, a three-fold increase in tonnage and two-fold in ships. In 1775, the first year of the war, the number of ships entering Bristol from America fell to 125; in 1780 it was just 1. The corresponding figures for ships clearing Bristol for North America were 57 and 9. Vessels entering Bristol from the West Indies also showed a decline, from 85 to 66 over the same period, so that the overall volume of incoming transatlantic trade was seriously affected by war. According to Ken Morgan's figures, it fell from an average of 21,202 tons in 1772–73 to 12,326 tons in 1778–80, the lowest level of trade since the War of Austrian Succession in the 1740s.

The result was lay-offs and higher poor rates. Without reciprocal trading, local businesses came under attack. Some serge and stuff-manufacturing firms collapsed; tobacco-pipe making for the American market disappeared. With a credit crisis in America and the reneging of many debts by American merchants and planters, bankruptcies also took their toll. There were over five hundred during the course of the war, at a rate three times as high as Liverpool. These included a number of leading Bristolians: Sir James Laroche, the master of the Merchant Venturers in 1782 and MP for Bodmin in Cornwall, 1768–80; the Farr brothers, prominent Presbyterian merchants from the Lewin's Mead chapel, one of whom (Thomas) was the mayor in 1775 while his brother (Paul) was the master of the Merchant Venturers.

It is possible to exaggerate the depth of the economic crisis, at least at the top of the merchant hierarchy.